Iron and Copper Release in Drinking-Water Distribution Systems
* Unlined metal pipes are widely used in drinking-water distribution systems.
* In the United States, more than 60 percent of distribution pipes are composed of cast iron, ductile iron, and steel.
* Copper pipe is a primary material for home plumbing systems.
* Corrosion of unlined metal pipes is ubiquitous.
* This corrosion can release contaminants that adversely affect health and water aesthetics.
* Corrosion results from chemical reactions between finished water and pipe metals or plumbing fixtures.
* It results in the formation of a solid corrosion product called scale.
* Disruption of solid scale is undesirable.
* Disruption typically releases more contaminants.
* If the composition of water frequently varies, the equilibrium between the corrosion scale and the water is disrupted, and contaminant release occurs.
* A pilot study at the University of Central Florida examined the effect on water quality of blending finished waters.
* Waters from ground, surface, and saline sources were used.
* The water treatment processes included
-- lime softening,
-- ferric sulfate coagulation,
-- reverse osmosis,
-- nanofiltration, and
-- integrated membrane systems.
* The waters were supplied to 18 pipe distribution systems (PDSs). …